Humans also get a Shield Proficiency and a Skill Proficiency, which is not nothing, though they are still underpowered. The problem, as I see it, is why? Why do all humans use Polearms better than other weapons? Why do humans use shields when many other races can't? It's just a dumb change from a flavor perspective.

Half-Elves are just as bad with the addition of Shield Proficiency, which is good for Sorcerers, but why?

Shield Dwarves should at least be able to use Shields, too. Right?